1. Field of the Invention
The present invention relates to a deinterlacing apparatus and method, and, more particularly, to deinterlacing apparatus and method to distinguish and adaptively interpolate, accordingly, still regions and moving regions in an image.
2. Description of the Related Art
The interlaced scan mode and the progressive scan mode are typical scan modes in an image display device. The interlaced scan mode has been employed in general TVs, and, as shown in FIG. 1A to FIG. 1C, is the mode that divides one image frame into two fields and interlaces the two fields sequentially and alternately on the screen when displaying one image. The two fields are called a top and a bottom field, an upper field and a lower field, an odd field and an even field, respectively, and, in FIG. 1A to FIG. 1C, the solid lines indicate lines being scanned at present, and the dotted lines indicate lines scanned for a preceding display.
The progressive or non-interlaced scan mode has been employed for computer monitors, digital TVs, and the like. The non-interlaces scan mode is the mode that sets one image frame as a frame unit and displays an entire frame at a time just like projecting films on the screen. That is, in FIG. 1A to FIG. 1C, it refers to the mode in which the dotted lines are sequentially scanned together with the solid lines.
The deinterlacing apparatus refers to an apparatus that converts an image signal of the progressive scan method into an image signal of the interlacing scan mode. In a display device processing an image signal of the progressive scan mode, in order for an image signal of the progressive scan mode to be processed normally, a deinterlacing apparatus is required inside the display device to convert an image signal of the progressive scan mode into an image signal of the interlacing scan mode.
A method converting the progressive scan mode into the interlacing scan mode can be implemented in various ways.
For a basic method, a line repetition method simply repeats line information of a present field. The method is implemented with ease, but has a drawback in that the resolution of an interpolated screen falls in the middle, and a specific image at a specific timing may completely disappear.
In order to overcome the above drawbacks, an intra-field interpolation method implementing new fields by inserting data obtained from dividing the data of two lines by two into a region between the two lines of a present field, an inter-field interpolation method without motion compensation which implements one frame by inserting lines before and after a present field between the lines of the present field, and the like have been developed. Such methods have an advantage of simple hardware implementations, but have disadvantages of making errors when interpolating motion images, and deteriorating interpolated images or an image quality.
In order to make up for the disadvantages of the above methods, a motion-compensated interpolation method has been developed which divides an image on the screen into plural blocks with respect to successive field data on a basis of present field data, obtains motions with respect to the respective blocks, and interpolates an image of a present frame with reference to motion vectors. Such a motion-compensated interpolation method is disclosed in U.S. Pat. No. 5,777,682 (Motion-compensated Interpolation, issued Jul. 7, 1998).
Also, there is a motion adaptive interpolation method which estimates the degree of motion and interpolates a frame based on the motion. Such a motion adaptive interpolation method is disclosed in U.S. Pat. No. 5,027,201 (Motion Detection Apparatus As For An Interlace To Non-interlace Scan Converter, issued Jun. 25, 1991), U.S. Pat. No. 5,159,451 (Field Memory Expansible Line Doubler For Television Receiver, issued Oct. 27, 1992), and the like.
However, the motion-compensated interpolation method generally uses a motion vector of a block unit to estimate a motion, causing block artifacts on an interpolated image from time to time, since an error correction is accomplished by a block unit. Accordingly, a post-processing process is necessary to prevent the block artifacts, which leads to a considerably more complicated hardware structure, causing the price to rise accordingly. Further, the motion adaptive interpolation method relatively simplifies a hardware structure, which costs less upon implementation, but has a problem of deteriorating the performance of the image quality improvements.